1. Field of the Invention:
This invention is an apparatus and a method for individually testing, measuring, and tuning a pair of active elements such as transistors that are paralleled in a circuit by means of quadrature couplers.
2. Description of the Prior Art:
U.S. Pat. No. 3,474,336 is a circuit for testing device X32 in conjunction with standard II 26 simultaneously. Hybrids A and B are employed; but no extra couplers are used as in the present invention, which is capable of testing parallel active devices independently and separately.
U.S. Pat. No. 3,711,769 tests unit 3 by removing the pure component of its output signal, leaving a spurious signal at the output of amplifier balance adjustment 5. The reference does not suggest the present invention.
U.S. Pat. No. 3,789,301 uses directional couplers, but only in conjunction with a single active device, to measure the parameters of the device at microwave frequencies.
Secondary references are U.S. Pat. Nos. 3,522,526 and 4,104,583.
None of the above references shows an apparatus and a method for independently measuring active elements that are paralleled via quadrature couplers.